The invention is useful in providing wide area networking services to clients with many locations among which data, especially high volumes of data, must be sent.
The prior art of WANs include frame relay and point-to-point networking offered by telephone companies. One type of Wide Area Network (WAN) service provided by telephone companies is leased lines. These may be analog or digital and are provide typically by a Local Exchange Carrier (LEC) on an intraLATA basis (Local Access and Transport Area). InterLATA leased lines are also available but must be provided by an Interexchange Carrier (IXC) with the LEC providing the local loop connection.
Another such WAN service is known as a Virtual Private Network. A VPN is intended for use by very large organizations with multiple locations. A VPN appears to the user as if it was private leased line trunk network, but it is not. VPN services are generally arranged with an Interexchange Carrier (IXC) with the points of the network termination (locations from which data will be sent and received being identified along with the level of bandwidth required at each termination. Dedicated circuits (telephone lines) are established between each network termination and the closest capable IXC POP (Point of Presence). Connections between POPS are not dedicated but are established by routers using routing tables to route the traffic over specified high-capacity transmission facilities on a priority basis to ensure the level of service provided is adequate and equivalent to a true private network using leased lines.
Other forms of Public Data Networks include: DDS, Switched 56 Kbps; Digital T-Carrier Systems; Digital 800 Services; X.25 Packet Switched Services; Broadband Data Networking such as Frame Relay and Cell Switching, ADSL, HDSL, Sonet, Switched Megabit Data Services, ISDN and Advanced Intelligent Networks.
Dataphone Digital Service (DDS) which was introduced by AT&T in 1974 and is generally end-to-end, fully digital, dedicated service provided my most carriers. DDS may be either point-to-point or multipoint. A head end Front End Processor controls all access to the network by polling remote devices. All communication must pass through the head end. DDS signals are carried within logical channels on T1 lines.
Switched 56 Kbps is a circuit switched (rather than dedicated line) digital service that serves the same applications as DDS although it is more cost effective for lower data volumes. All the components are the same as DDS but digital local loops and digital carrier exchanges are used. The main difference over DDS is that traffic is routed using a logical address which is the equivalent of a voice telephone number. The circuit is set up, maintained and torn down much like a voice call is switched and pricing is similar. The cost is sensitive to distance, duration, time of day and day of the year.
Digital T-carrier systems (including fractional T1 service) are dedicated links carry digital data over multiple logical channels on a single physical communication circuit with the logical channels established by time division multiplexing.
Digital 800 service was introduced in 1994 by AT&T and is intended for medium to high volume customers subscribing to high volume 800 service offerings.
X.25 packet switching was invented in the early 60's and was implemented on ARPANET in 1971. X.25 is a dial up service as is ISDN and Switched 56/64 Kbps WANS, and, as such, is not suitable for dedicated WANs such as the WANs in the AlterWAN™ network genus of the invention. The basic concept of packet switching provides a highly flexible, shared network in support of interactive computer communications in a WAN. Prior to packet switching, users spread over a wide area with only infrequent traffic had no cost effective way of sharing computer resources. Asynchronous communications are bursty in nature and send only small amounts of data with lots of idle time between bursts. Having dedicated lines for such communication is a waste of bandwidth and expensive. Packet switching solved those problems by providing connections as needed which were billed on the number of packets transmitted. Packet switching also improved the error performance. Typically a packet switched network uses a dial up connection to a packet switching node. Once the connection to packet switching node is made, a control packet is sent to establish the session with the target host. The control packet is forwarded across the most direct link that is available in a number of hops between nodes. The target host responds with a control packet sent back to the source to establish the session. Each packet is numbered sequentially and transmitted. ISDN is an entirely digital suite of dial-up data communication services delivered over the twisted pair local loop. ISDN lines have B channels that carry information, D-channels that carry data for signalling and control, H-channels that carry high speed data for bandwidth intensive applications. It has been a commercial failure.
Frame relay networks were first deployed in the mid 90's and are somewhat like packet switching in that each frame is individually addressed. Frame relay makes use of special switches and a shared network of very high speed. Unlike packet switching, frame relay supports the transmission of virtually any computer data stream. Frames are variable in length up to 4096 bytes. Frame relay is data oriented and does not support voice or video very well. As is the case for X.25 packet switching, frame relay overhead is high and delays in transmission are expected. Further, network congestion can result in loss of data. Although frame relay networks appear to the customer to be one-hop networks, they really are not one hop nets. There are many links between multiple Central Office (CO) switches inside the typical frame relay cloud. Each hop adds latency and the possibility of running into bandwidth congestion. Further, frame relay networks cannot cross telephone company boundaries so all sites on a frame relay WAN must be using the same frame relay provider, i.e., it not possible for some sites to be coupled to AT&T frame relay COs and other sites to be coupled to MCI or Sprint COs. Every frame has a DLCI code in the header that identifies the customer and the virtual data path through a particular telephone company for the traffic. Therefore, it is not possible to mix frames with different DLCIs because different telco DLCIs have different formats and that will disrupt the routing process for such frames through the CO switches. If two locations on a frame relay network cannot both be served by the same frame relay provider, a second frame relay cloud must be built and the two clouds connected together by two routers at some common location that can be coupled to both clouds with the two routers coupled together by a local area network.
Cell switching has been conventionally thought to be the future of data communication networks. Cell switching encompasses both ATM networks and Switched Multimegabit Data Service (SMDS). Data is organized into cells of fixed length of 53 octets and are shipped across high speed facilities and switched in high speed, specialized switches. ATM is primarily data oriented, but is supports voice and video effectively. Cell switching is high cost and has high overhead and suffers from a lack of fully developed standards. ATM networks are also not widely commercially available yet.
The problem with all these approaches is that they are expensive with recurring telephone company charges.
The internet as a backbone has recently loomed as a possibility for implementing wide area networks and lowering the cost. However, there are several problems with using the internet as a WAN backbone. Generally, these problems all relate to quality of service. Quality of service has to do with both errors in transmission as well as latency. Latency or delay on critical packets getting from source to destination can seriously slow or disrupt operations of computer systems. Latency can also destroy the efficacy of streaming video, streaming audio and streaming multimedia product and service delivery by causing visible and/or audible gaps in the presentation of the program encoded in the data to the user or freezes. This can be very distracting and undesirable in, for example, video conferences, video-on-demand, telephone calls etc. Latency is also a problem when large documents are being downloaded because it slows the process considerably. Latency arises from multiple hops between nodes on the internet coupling the source to the destination.
Prior art attempts to use the internet as a backbone did not control the number of hops and available bandwidth in the data path from source to destination. As a result the number of router hops along the route and the lack of available bandwidth precluded the use of the internet as a viable private network backbone alternative. ISP's built local businesses without regard to the customers regional, national or international presence as their objective was only to offer LOCAL internet access. This resulted in attempts to use the internet as an alternative private network backbone of routes that may have few hops or many hops. Routes that may have inadequate bandwidth for the worst case bandwidth requirement of a WAN were sometimes picked and that resulted in failure. This uncontrolled hop count, and lack of control of the data paths and the available bandwidth and the resulting latency caused problems in implementing WANs on the internet.
Another major problem with using the internet as a backbone is security or privacy. Since the internet is a public facility, private and sensitive data transmitted over the internet is subject to snooping.
Thus, there has arisen a need for a system which can use the internet as a WAN backbone to help decrease the costs of data transport while not suffering from the aforementioned latency, privacy and bandwidth availability problems.